Electronic fluid pump

ABSTRACT

A fluid pump includes a pump housing having a housing cavity with an inlet and an outlet. An encapsulated stator assembly is positioned within the housing cavity and at least partially defines a fluid passage from the inlet to the outlet. A polymeric capsule member encloses and seals the encapsulated stator assembly, protecting the motor from, and providing heat transfer to, the working fluid. A stator provides a magnetic field which drives a rotor assembly. The rotor assembly rotates an impeller for pumping fluid from the inlet to the outlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/777,391 filed Feb. 5, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a fluid pump containing anencapsulated stator assembly that seals a pump motor and facilitatesheat transfer from the motor and the electronics to the working fluid.

[0004] 2. Background Art

[0005] Use of fluid pumps in vehicle engine cooling systems and variousindustrial applications is well known. However, typical fluid pumps inboth of these areas have inherent limitations.

[0006] Typically in engine cooling systems, a coolant pump has a pulleykeyed to a shaft. The shaft is driven by the engine via a belt andpulley coupling, and rotates an impeller to pump the working fluid.Fluid seals sometimes fail due to the side load from the drive belt,which tends to allow fluid to leak past the seal into the bearing.

[0007] U.S. Pat. No. 6,056,518, issued on May 2, 2000 to Allen et al.,describes one attempt to overcome the shortcomings of prior art vehiclecoolant pumps. The '518 patent provides a fluid pump with a switchedreluctance motor that is secured to a housing and rotates an impellerfor pumping the fluid. This design eliminates the side load problemassociated with keyed pulleys, but it is generally not intended for usewhere larger industrial pumps are required.

[0008] Industrial pumps are typically driven by an electric motorconnected to the pump via a coupling, the alignment of which iscritical. Misalignment of the coupling can result in premature pumpfailure, which leads to the use of expensive constant velocity couplingsto overcome this problem. Moreover, industrial pumps are typicallyair-cooled, relying on air from the surrounding environment. The coolingair is drawn through the motor leaving airborne dust and othercontaminants deposited in the motor. These deposits can contaminate thebearings, causing them to fail, or the deposits can coat the windings,shielding them from the cooling air and causing the windings to overheatand short out.

[0009] Accordingly, it is desirable to provide an improved fluid pumpwhich overcomes the above-referenced shortcomings of prior art fluidpumps, while also providing enhanced fluid flow rate and controlcapability while reducing costs.

SUMMARY OF THE INVENTION

[0010] The present invention provides a fluid pump with an encapsulatedstator assembly that contains a rotor cavity. A rotor assembly, drivenby a stator, is positioned within this cavity and turns an impeller forpumping the working fluid. The encapsulated stator assembly prevents theworking fluid from directly contacting the motor. It does, however, havean outside wall that is in contact with the working fluid, therebyfacilitating heat transfer from the motor to the fluid.

[0011] More specifically, the present invention provides a fluid pumpincluding a housing having a housing cavity therein. An encapsulatedstator assembly is positioned within the housing cavity and at leastpartially defines a boundary for the working fluid. The encapsulatedstator assembly contains a rotor cavity in which a rotor assembly islocated. The magnetic field generated by a stator drives the rotorassembly, which is connected to an impeller for pumping the fluid.

[0012] In a preferred embodiment, the encapsulated stator assembly is asingle unit, and is located inside a two-piece housing. A statorcomprising steel laminations, windings, and motor power leads, isencapsulated in a thermally conductive, electrically insulativepolymeric capsule member. The polymeric capsule member defines a rotorcavity having an opening. The rotor assembly, consists of a rotor with arotor shaft, the rotor shaft being supported by a front bearing and arear bearing. Also, in the preferred embodiment, the rear bearing islocated within the encapsulated stator assembly, and the front bearingand a seal are positioned within a front cover that plugs the rotorcavity opening.

[0013] A diffuser is used to help direct fluid flow and thereby increasethe efficiency of the pump. The diffuser comprises an inner wall, anouter wall, and a plurality of diffuser vanes. The diffuser vanes areintegrally molded to the outer wall of the encapsulated stator assembly.The polymeric capsule member orients the motor power leads withsubstantial circumferential symmetry around the diffuser. The motorpower leads then interface with a circuit board assembly near the outletof the pump. The working fluid flows around the outside of theencapsulated stator assembly, thereby encountering the diffuser vanesand allowing heat transfer from the motor to the fluid. The workingfluid then encounters the encapsulated motor power leads, therebycooling both the motor power leads and the circuit board assembly.

[0014] In an alternative embodiment, the one piece encapsulated statorassembly is replaced with a one piece stator housing assembly. Thischange allows for larger motors to be utilized with the pump, andthereby increases the number of applications in which the invention maybe used. The stator housing assembly includes an encapsulated statorassembly and a substantially cylindrical metal case which provides anoutlet for a single bundle of motor power leads and also containsdiffuser vanes that fully define the boundary of the working fluid. Theencapsulated stator assembly is enclosed and sealed by a thermallyconductive, electrically insulative polymeric capsule member thatdefines a motor cavity and provides a heat transfer path to the workingfluid. As in the preferred embodiment, a rotor with a rotor shaft islocated in the motor cavity and is driven by the magnetic fieldgenerated by the stator. The motor housing assembly comprises a frontcover, a stator housing assembly, and a rear cover.

[0015] This alternative embodiment also has a diffuser with diffuserwalls and diffuser vanes; however, there are now two sets of diffuservanes. The front cover is configured with a first set of diffuser vanesand the stator housing assembly is configured with a second set ofdiffuser vanes. The two covers and the stator housing assembly arejoined together and sealed in a manner to prevent the working fluid fromentering the motor cavity.

[0016] Accordingly, an object of the present invention is to provide afluid pump with an encapsulated stator assembly, the encapsulated statorassembly orienting the motor components and providing heat transferbetween the motor and the working fluid.

[0017] Another object of the invention is to provide a fluid pump withan encapsulated stator assembly, the encapsulated stator assemblyforming a diffuser, including a plurality of diffuser vanes. The aboveobject and other objects, features, and advantages of the presentinvention are readily apparent from the following detailed descriptionof the best mode for carrying out the invention when taken in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 shows a longitudinal cross-sectional view of a fluid pumpin accordance with the present invention;

[0019]FIG. 2 shows a longitudinal cross-sectional view of anencapsulated stator assembly for use with the pump shown in FIG. 1;

[0020]FIG. 3 shows a perspective view of the encapsulated statorassembly, with the motor cavity opening toward the front and the motorpower leads toward the back;

[0021]FIG. 4 shows a rear perspective view of an impeller for use withthe pump shown in FIG. 1;

[0022]FIG. 5 shows a perspective view of a two piece pump housing withan inlet housing toward the front and an outlet housing toward the rearfor use with the pump shown in FIG. 1;

[0023]FIG. 6 shows a perspective view of the outlet housingcorresponding with the embodiment of FIG. 1;

[0024]FIG. 7 shows a perspective view of the outlet housing of FIG. 6,with a circuit board assembly attached;

[0025]FIG. 8 shows a side view of a fluid pump in accordance with analternative embodiment of the invention;

[0026]FIG. 9 shows a longitudinal cross-sectional view of the fluid pumpshown in FIG. 8;

[0027]FIG. 10 shows a perspective view of the stator housing assembly ofthe fluid pump of FIG. 8;

[0028]FIG. 11 shows a longitudinal cross-sectional view of the statorhousing assembly of FIG. 10;

[0029]FIG. 12 shows a longitudinal cross-sectional view of a secondalternative embodiment of the fluid pump of FIG. 1;

[0030]FIG. 13 shows a longitudinal cross-sectional view of a sealcartridge assembly for use with the pump shown in FIG. 12;

[0031]FIG. 14 shows a perspective view of the seal cartridge assemblyand one end of the rotor shaft with a drive pin for use with the pumpshown in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0032]FIG. 1 shows a longitudinal cross-sectional view of a fluid pump10 in accordance with the present invention. A two-piece pump housingcomprises an inlet pump housing 12 and an outlet pump housing 14. Thepump housing has a housing cavity 15 therein which contains anencapsulated stator assembly 22.

[0033] Referring to FIG. 2, the encapsulated stator assembly 22 definesa rotor cavity 17 with an opening 19. The encapsulated stator assembly22 comprises a polymeric capsule member 21, that has a plurality ofdiffuser vanes 18 molded integrally thereon. Polymeric capsule member 21encloses and seals a motor stator 20 and motor power leads 32. Thus,when the fluid pump 10 is used in an engine cooling system, the motorstator 20 and motor power leads 32 are protected from the liquid enginecoolant. Motor stator 20 comprises a plurality of steel laminations 20 aand a plurality of copper windings 20 b.

[0034] Returning to FIG. 1, located within rotor cavity 17 is a rotorassembly 28, consisting of a rotor 28 a and a rotor shaft 28 b. Therotor shaft 28 b is supported by a front bearing 42 and a rear bearing40. Rear bearing 40 is located within the encapsulated stator assembly22. Front bearing 42 and seal 44 are located within the front cover 26that plugs the rotor cavity opening 19.

[0035]FIG. 3 shows a front perspective view of encapsulated motorassembly 22. In particular, it shows diffuser vanes 18 which are ofsplit construction (but need not be of split construction for thisinvention), and the motor power leads 32 which are oriented withsubstantial circumferential symmetry around the longitudinal axis of theencapsulated stator assembly 22. As seen in FIG. 1, motor power leads 32interface with a circuit board assembly 34.

[0036] Returning to FIG. 1 impeller 16 is slip fit onto the rotor shaft28 b and secured with a buttonhead capscrew 50. A drive pin 30transversely located through rotor shaft 28 b drives impeller 16 viaslot 23.

[0037]FIG. 4 shows impeller 16 with slot 23 configured to receive drivepin 30. FIG. 5 shows the inlet pump housing 12 attached to the outletpump housing 14. Outlet pump housing 14 is again shown in FIG. 6, thistime with motor power leads 32. FIG. 7 shows the outside of pump 10including the inlet pump housing 12, the outlet pump housing 14, thecircuit board assembly 34, and the connection points between circuitboard assembly 34 and the motor power leads 32.

[0038] Referring to FIG. 8, a fluid pump 60 is shown in accordance withone alternative embodiment of the invention. Although similar infunction to the preferred embodiment, there are a number of notabledifferences with regard to form. Rather than a two-piece housing, thisembodiment employs a three-piece housing comprising an inlet housing 62,a stator housing assembly 64, and an outlet housing 66, assembled withbolts 68.

[0039] The stator housing assembly 64, shown in FIG. 10 and sectioned inFIG. 11, includes an encapsulated stator assembly 75 and a substantiallycylindrical metal case 73 which provides an outlet for a single bundleof motor power leads 92 and diffuser vanes 83 that fully define theboundary of the working fluid. The encapsulated stator assembly 75includes a plurality of steel laminations 90 a, a plurality of windings90 b, and a plurality of motor power leads 92. A polymeric capsulemember 77 encloses and seals the stator assembly 90, and also defines arotor cavity 79.

[0040] As shown in FIG. 9, a rotor assembly 82, consisting of a rotor 82a and a rotor shaft 82 b, is located within rotor cavity 79. Rotor shaft82 b is supported by a rear bearing 96 positioned within the rear cover74 which plugs the rear opening of the rotor cavity 79, and a frontbearing 86 and seals 100 positioned within a front cover 70 which plugsthe forward opening of the rotor cavity 79. Drive pin 84 is positionedtransversely through rotor shaft 82 b and drives impeller 76.

[0041] Referring to FIG. 9, unlike the preferred embodiment, thisalternative embodiment has two separate sets of diffuser vanes, thefirst set 81 being configured on the front cover 70 and the second set83 being configured on the stator housing assembly 64.

[0042]FIGS. 10 and 11 clearly show the resultant fluid passage 88 formedbetween the vanes 83 and the inner and outer walls 73 a,73 b of themetal case 73.

[0043] The encapsulated stator assembly 75 may be manufactured bylocating the stator assembly 90 within the substantially cylindricalmetal case 73 and temporarily capping the two open ends of the metalcase. The stator assembly 90 would then be encapsulated in a polymericthermally conductive, electrically insulative material 77. The opposingends of the metal case would be uncapped, and the front and rear covers70,74 would be attached to the metal case to complete the encapsulatedstator assembly 75.

[0044]FIG. 12 shows a second alternative embodiment of the fluid pump ofFIG. 1. Seal cartridge assembly 26 plugs opening 19 in rotor cavity 17.Wear sleeve 24 is slip fit over the end of rotor shaft 52 b. An impeller16 is slip fit onto wear sleeve 24 and is secured to rotor shaft 52 bwith a buttonhead capscrew 50. A drive pin 30 transversely locatedthrough rotor shaft 52 b and wear sleeve 24 serves multiple functions.The drive pin 30 drives impeller 16 via slot 23 (similarly as shown inFIG. 4); it prevents wear sleeve 24 from rotating relative to rotorshaft 52 b; it captures axial loads from rotor assembly 52.

[0045] Some of the features and components of the seal cartridgeassembly 26 are shown in FIGS. 12 and 13. Body 27 has a wet side 31 incontact with the working fluid, such as a liquid engine coolant, and adry side 29. The body 27 also contains a plurality of holes 47 forattaching the seal cartridge assembly 26 to the encapsulated statorassembly 57, using bolts 48. A seal 53 is press fit into the body 27 andplugs an opening on the wet side 31.

[0046] Referring to FIG. 14, the wear sleeve 24 is machined to form aninner diameter and has an axis coaxial to an axis of the body 27. A hole25 is machined transverse to the wear sleeve axis and is configured toreceive drive pin 30. The rotor shaft 52 b has a transverse hole 56 thatalso receives drive pin 30.

[0047] Returning to FIG. 13, the front bearing 51, being press fit ontothe substantially cylindrical wear sleeve 24, plugs an opening on thedry side 29. The bearing 51 and wear sleeve 24 are press-fit into thecartridge body, and the wear sleeve 24 is slip fit over the shaft 52 b.The seal cartridge assembly 26 also contains leak detection ports 33,shown in FIG. 14, for visual or electronic indication of seal 53failure.

[0048] While embodiments of the invention have been illustrated anddescribed, it is not intended that these embodiments illustrate anddescribe all possible forms of the invention. Rather, the words used inthe specification are words of description rather than limitation, andit is understood that various changes may be made without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A fluid pump for pumping liquid, comprising: ahousing having a housing cavity therein with an inlet and an outlet; anencapsulated stator assembly positioned in the housing cavity tocooperate with the housing and to at least partially define a liquidpassage from the inlet to the outlet; wherein the encapsulated statorassembly is enclosed and sealed from the pumped liquid by a polymericcapsule member and the polymeric capsule member defines a rotor cavityhaving an opening; an impeller rotatably positioned at the inlet andhaving an impeller axis; and a rotor assembly rotatably located insidethe rotor cavity and connected to the impeller for rotating the impellerfor pumping liquid through the passage from the inlet to the outlet. 2.The fluid pump of claim 1, wherein the rotor assembly is sealinglyprotected from the liquid by a seal cartridge assembly, the sealcartridge assembly being positioned within the opening.
 3. The fluidpump of claim 1, wherein the polymeric capsule member comprises athermally conductive, electrically insulative material.
 4. The fluidpump of claim 1, wherein the encapsulated stator assembly comprises aplurality of steel laminations, a plurality of copper windings, and aplurality of motor power leads.
 5. The fluid pump of claim 4, whereinthe polymeric capsule member orients the motor power leads withsubstantial circumferential symmetry around the impeller axis.
 6. Thefluid pump of claim 4, further comprising a circuit board assemblylocated near the outlet and interfacing with the motor power leads. 7.The fluid pump of claim 1, further comprising a diffuser, wherein thediffuser comprises an inner wall formed by an outer wall of theencapsulated stator assembly, an outer wall formed by an inner wall ofthe housing, and a plurality of diffuser vanes.
 8. The fluid pump ofclaim 7, wherein the outer wall of the encapsulated stator assembly isconfigured with the diffuser vanes.
 9. The fluid pump of claim 1,wherein the rotor assembly includes a rotor with a rotor shaft.
 10. Thefluid pump of claim 9, wherein the rotor shaft is supported by a frontbearing and a rear bearing.
 11. A fluid pump for pumping liquid,comprising: a housing having a housing cavity therein with an inlet andan outlet; an encapsulated stator assembly enclosed and sealed by apolymeric capsule member, wherein the polymeric capsule member defines arotor cavity having an opening; an impeller rotatably positioned at theinlet and having an impeller axis; a rotor assembly rotatably locatedinside the rotor cavity and connected to the impeller for rotating theimpeller for pumping liquid through the passage from the inlet to theoutlet; and a seal cartridge assembly positioned within the opening forsealing the rotor assembly within the rotor cavity.
 12. The fluid pumpof claim 11, wherein the polymeric capsule member comprises a thermallyconductive, electrically insulative material.
 13. The fluid pump ofclaim 11, wherein the encapsulated stator assembly comprises a pluralityof steel laminations, a plurality of copper windings, and a plurality ofmotor power leads.
 14. The fluid pump of claim 13, further comprising acircuit board assembly located near the outlet and interfacing with themotor power leads.
 15. The fluid pump of claim 11, further comprising adiffuser, wherein the diffuser comprises an inner wall formed by anouter wall of the encapsulated stator assembly, an outer wall formed byan inner wall of the housing, and a plurality of diffuser vanes.
 16. Thefluid pump of claim 15, wherein the outer wall of the encapsulatedstator assembly is configured with the diffuser vanes.
 17. The fluidpump of claim 11, wherein the rotor assembly includes a rotor with arotor shaft.
 18. The fluid pump of claim 17, wherein the rotor shaft issupported by a front bearing and a rear bearing.
 19. A fluid pump forpumping liquid, comprising: a housing having a housing cavity thereinwith an inlet and an outlet; an encapsulated stator assembly positionedin the cavity, wherein an outer wall of the encapsulated stator assemblyforms an inner boundary of the liquid flow path and an inner wall of thehousing forms an outer boundary of the liquid flow path; wherein theencapsulated stator assembly is enclosed and sealed by a polymericcapsule member and the polymeric capsule member defines a rotor cavityhaving an opening; wherein a plurality of motor power leads are encasedin the encapsulated stator assembly; and wherein the motor power leadsare at least partially within the liquid flow path for cooling the motorpower leads.
 20. The fluid pump of claim 19, wherein the rotor assemblyis sealingly protected from the liquid by a seal cartridge assembly, theseal cartridge assembly being positioned within the opening.
 21. Thefluid pump of claim 19, wherein the polymeric capsule member comprises athermally conductive, electrically insulative material.
 22. The fluidpump of claim 19, wherein the polymeric capsule member orients the motorpower leads with substantial circumferential symmetry around theimpeller axis.
 23. The fluid pump of claim 19, further comprising acircuit board assembly located near the outlet and interfacing with themotor power leads.
 24. The fluid pump of claim 19, further comprising adiffuser, wherein the diffuser comprises an inner wall formed by theouter wall of the encapsulated stator assembly, an outer wall formed bythe inner wall of the housing, and a plurality of diffuser vanes. 25.The fluid pump of claim 24, wherein the outer wall of the encapsulatedstator assembly is configured with the diffuser vanes.
 26. The fluidpump of claim 19, wherein the rotor assembly includes a rotor with arotor shaft.
 27. The fluid pump of claim 26, wherein the rotor shaft issupported by a front bearing and a rear bearing.
 28. A fluid pump forpumping liquid, comprising: a housing having a housing cavity thereinwith an inlet and an outlet; an encapsulated stator assembly enclosedand sealed by a polymeric capsule member, wherein the polymeric capsulemember defines a rotor cavity having an opening; and wherein thepolymeric capsule member comprises a thermally conductive, electricallyinsulative material.
 29. The fluid pump of claim 28, wherein theencapsulated stator assembly comprises a plurality of steel laminations,a plurality of copper windings, and a plurality of motor power leads.30. The fluid pump of claim 29, further comprising a circuit boardassembly located near the outlet and interfacing with the motor powerleads.
 31. The fluid pump of claim 28, further comprising a diffuser,wherein the diffuser comprises an inner wall formed by an outer wall ofthe encapsulated stator assembly, an outer wall formed by an inner wallof the housing, and a plurality of diffuser vanes.
 32. The fluid pump ofclaim 31, wherein the outer wall of the encapsulated stator assembly isconfigured with the diffuser vanes.
 33. A fluid pump for pumping liquid,comprising: a housing having a housing cavity therein with an inlet andan outlet; an impeller rotatably positioned at the inlet and defining animpeller axis, the impeller including a slot oriented substantiallyperpendicular to the impeller axis; an encapsulated stator assemblyenclosed and sealed by a polymeric capsule member, the encapsulatedstator assembly including a plurality of steel laminations, a pluralityof copper windings, and a plurality of motor power leads, the polymericcapsule member defining a rotor cavity having an opening and including athermally conductive, electrically insulative material, the motor powerleads exiting the housing through a side of the housing; a rotorassembly disposed inside the rotor cavity and connected to the impellerfor rotating the impeller for pumping liquid through the passage fromthe inlet to the outlet, the rotor assembly including a rotor and arotor shaft; a drive pin transversely disposed through the rotor shaftand configured to cooperate with the impeller slot for driving theimpeller; front and rear bearings disposed on opposite ends of the rotorshaft for rotatably supporting the rotor shaft; and a diffuser includinga plurality of diffuser vanes, each of the diffuser vanes being of splitconstruction and having a portion substantially parallel to the impelleraxis.